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Compression increase stock 73, 302 ci
#1
tach 
Dear friendswelcomeAs part of my restoration plan (see potos, high corrosion), will improve POWER!, some at least, only for street pleasure. Want to install new cylinder heads (E-Street form Edelbrock in example with 60 cc combustion chamber), new Performer intake (dual plane, low rise), new cam (want COMP, rough idle), and compression increase to be able to install above kit and a Mutha Thumpr, both requires 9.1:1.
Is a stock car, probably 8.0:1, has T5 tranny (converted from FMX), HEI Ignition, 17" wheels, front disc power brakes, have a 600 cfm Holley, and double exhaust pipes. Will also put new hydraulic flat tappets.
Help needed: What size is the combustion chamber of a stock , coupe 1973, 302 ?. Will 60 cc chambers help compression increase? What actions are recommended to reach 9:1? Edelbrock says power can go over 300 with above top end kit and 9.1:1, any practical reference out there?
Thanks!!!!!


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#2
The 69-70 D0OE heads are 58cc, and are good heads if you can find them. The Stock 73 302 heads are IIRC 64-66cc though seeing an actual 7cc variation between the same pair of heads is not unheard of.
So the 60cc heads your looking at should put you into the 9.0ish CR range. The same heads in 58cc would be no more expensive, should put you into the 9.5-9.7 range which would be more torque. Remember HP is what you lie to your buddies about, torque is what gets you from stoplight to stoplight.

If you relly want more power, change to a lower gear ratio, add an over drive tranny to keep it happy on the highway.

Tubo
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#3
Tubo;129653 Wrote:If you relly want more power, change to a lower gear ratio, add an over drive tranny to keep it happy on the highway.

Tubo

That's what I'm doing dancebanana

3.89 rear end with a 4-speed wide ratio AOD.

I figure my '73 motor puts out around 200HP, but has probably closer to 250-275lbs of torque.

BTW, the Edlebrock Performer intake along wih their Performer or Thunder Series carb is a pretty sweet setup!
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#4
Hello Jarturin,

Your 1973 302 cylinder heads likely has 9.5 CR with 140 Hp @ 4000RPMs.

Cylinder Heads
D20E-BA 72-74 302 >>>1.78, 1.45 with 58.2

Here is my recommendation.

1: Keep the 1973 Cylinder Block – Has much more nickel content than today’s 5.0 302 engines.

2: Keep the old 1973 cylinder heads for prosperity purposes. Trash the Edelbrock - E-Street 170 due to limitations of having to use flat tappet camshaft.

3: Look at the Flo Tek Small Block Ford 5.0X Cylinder heads >Stud & Plate Assembled
http://www.flootek.com/product/small-blo...assembled/

4: Buy a roller cam conversion kit> COMP Cams/Hydraulic roller Retro-Fit kit for Ford 289-302, 351C, 351M, 351W and 400 cid. includes lifter guides, lifter retainer and socket head cap screws
http://www.autozone.com/autozone/accesso...85684_0_0_

5: Camshaft> That depends on your taste.

6: Locate a nice SCAT engine kit-
http://www.probeindustries.com/Ford_302_.../30113.htm

7: A nice High volume oil pump with stud griddle.

Brothers Performance
http://www.brothersperformance.com/ford-...bikEtjAtCI

Melling high-volume oil pumps : additional 20 to 25 percent of much-needed oil volume for your performance application
http://www.summitracing.com/search/Produ.../5-0L-302/

8: Intake Manifold: Professional Products SB Ford Crosswind Satin. The CrossWind design incorporates an open area under the plenum to allow a full flow of cooling air to pass through

http://www.professional-products.com/Hom...-p274.html

9: Fuel system Tonguerofessional Products PowerInjection III- http://www.professional-products.com/Pow...n-III-c68/

10: Distributor : Mallory Unilte with Hy-Fire Spark Box

Mallory: http://mallory-ignition.com/dist-ford-v8...il-va.html

HyFire: http://mallory-ignition.com/hyfire-6a-di...ition.html

11: Edelbrock 7892 - Edelbrock Accu-Drive Timing Gear Drive
http://www.jegs.com/i/Edelbrock/350/7892...tId=746083

12: Harmonic Balancer:
Powerforce and Powerforce+Plus Small Block Ford dampers are all made to the 1963-1969 length.
http://www.professional-products.com/Hom...-Ford-c49/

Well, that is a start! Highly recommend to Balance the rotating assembly. What a kit.

Mustang7173
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#5
Thanks Tubo for your data, please teach me how you arrive to 9+:1.
Looking more at Internet, found input from EDDYW, who reported an AMA file with full specs for 73, could somebody explain meaning of concepts there specifying " cylinder head volume = 56.7 to 59.7 cc", and "minimum combustión chamber = 83.2". How this connects with compression change estimates?

Also found another info from JC Whitney about Mustang and Shelby specs that says for 73, 302, 2 bbl, torque = 242 @ 2000, HP= 141 @ 4000 and compression = 8.5:1.
Then I will start stating that comp is 8.5 : 1 originally.



Regarding input from Mustang7173, whow!, great plan!, but I am budget limited so will keep it simple.

Anyhow, please explain "Cylinder Heads 1.78, 1.45 with 58.2"

Thanks again.
  Reply
#6
mustang7173 is referring to valve diameter and volume of combustion chamber. remember an increase in compression = higher octane fuel. so if I were you I would follow tubo's advice...that's my 2 cents
  Reply
#7
The combustion chamber volume includes the cylinder head volume, the volume created by the gasket, the volume from the top of piston to the top of cylinder, and the volume of any valve reliefs or dishes in the piston.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#8
Hello Jarturin,

Well, I know about Budgets. Maybe a small amount of milling of the heads will increase combustion chamber. I mean just a bit. You mill too much off, then you have to have shorter push rods. Also, converting to roller cam shaft should not be too expensive. It is well worth it. Since tappet cams still need the zinc, which is non existence in modern oil today.

mustang7173
  Reply
#9
I gave you the 9.0 CR estimate by experience. I was pretty sure the 73 F code 302 has a CR of 8.5 w/combustion chamber of 64cc, so using a combustion chamber 2-3cc smaller would increase the CR about 1/2 a point. Is a volume ratio effect, starting with a 54-58cc set of heads and reducing combustion chamber size the same 2-3cc would yield a more dramatic CR change.
Mustang7173 is right about milling the heads, though talk to the machinest to get accurate measurments of combustion chamber volume change with a milling of .002 or so. Again the machinest makes his living doing this and will have the most accurate answers.
  Reply
#10
mustang7173;129659 Wrote:Hello Jarturin,

Your 1973 302 cylinder heads likely has 9.5 CR with 140 Hp @ 4000RPMs.

Cylinder Heads
D20E-BA 72-74 302 >>>1.78, 1.45 with 58.2

Here is my recommendation.

1: Keep the 1973 Cylinder Block – Has much more nickel content than today’s 5.0 302 engines.

2: Keep the old 1973 cylinder heads for prosperity purposes. Trash the Edelbrock - E-Street 170 due to limitations of having to use flat tappet camshaft.

3: Look at the Flo Tek Small Block Ford 5.0X Cylinder heads >Stud & Plate Assembled
http://www.flootek.com/product/small-blo...assembled/

4: Buy a roller cam conversion kit> COMP Cams/Hydraulic roller Retro-Fit kit for Ford 289-302, 351C, 351M, 351W and 400 cid. includes lifter guides, lifter retainer and socket head cap screws
http://www.autozone.com/autozone/accesso...85684_0_0_

5: Camshaft> That depends on your taste.

6: Locate a nice SCAT engine kit-
http://www.probeindustries.com/Ford_302_.../30113.htm

7: A nice High volume oil pump with stud griddle.

Brothers Performance
http://www.brothersperformance.com/ford-...bikEtjAtCI

Melling high-volume oil pumps : additional 20 to 25 percent of much-needed oil volume for your performance application
http://www.summitracing.com/search/Produ.../5-0L-302/

8: Intake Manifold: Professional Products SB Ford Crosswind Satin. The CrossWind design incorporates an open area under the plenum to allow a full flow of cooling air to pass through

http://www.professional-products.com/Hom...-p274.html

9: Fuel system Tonguerofessional Products PowerInjection III- http://www.professional-products.com/Pow...n-III-c68/

10: Distributor : Mallory Unilte with Hy-Fire Spark Box

Mallory: http://mallory-ignition.com/dist-ford-v8...il-va.html

HyFire: http://mallory-ignition.com/hyfire-6a-di...ition.html

11: Edelbrock 7892 - Edelbrock Accu-Drive Timing Gear Drive
http://www.jegs.com/i/Edelbrock/350/7892...tId=746083

12: Harmonic Balancer:
Powerforce and Powerforce+Plus Small Block Ford dampers are all made to the 1963-1969 length.
http://www.professional-products.com/Hom...-Ford-c49/

Well, that is a start! Highly recommend to Balance the rotating assembly. What a kit.

Mustang7173

mustang7173... that is one hell of a post, great info with web links. Reps coming your way...

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